1. Field of the Invention
The present invention relates to a thermal development diazo copying material capable of developing latent images formed thereon with the application of heat thereto, which latent images are formed with the thermal development diazo copying material being exposed to light with a transparent or semitransparent image-bearing original being superimposed thereon. The present invention also relates to a thermosensitive recording material on which images can be fixed by the application of light thereto.
1. Discussion of Background
A conventional thermal development diazo copying material is generally composed of a support such as a sheet of paper, or a film, and a photosensitive layer formed thereon, which is mainly composed of a diazo compound, a coupling component, and a coloring auxiliary agent. As such a coloring auxiliary agent, for example, urea and sodium trichloroacetate are employed.
In any diazo copying materials of this kind, latent images are developed by the application of heat to 180.degree. to 200.degree. C. In these copying materials, an alkaline component formed by thermal decomposition of the coloring component contained therein is utilized in the development mechanism.
In an attempt to decrease the development temperature, a thermofusible material such as a higher fatty acid amide is employed as a coloring auxiliary agent. In this development mechanism, the activation of a diazo compound and a coupling component by the thermal fusion thereof is utilized.
Conventional thermal development diazo copying materials, however, have the shortcoming that the precoupling of a diazo compound and a coupling component gradually proceeds during the preservation thereof so that the copying materials become colored.
In order to eliminate this shortcoming, it has been proposed that one of a diazo compound, a coupling component or an alkaline generating agent is contained in the form of discontinuous particles to prevent the mutual contact of the above components, thereby avoiding the precoupling, for instance, in Japanese Laid-Open Patent Applications 57-42042, 57-45094, and 57-125091.
However, the above-mentioned method still has the problem that the preservation of the thermal development diazo copying material is insufficient for use in practice.
Furthermore, Japanese Laid-Open Patent Applications 57-44141 and 59-190886 disclose methods by which any of a diazo compound, a coupling component or an alkaline generating agent is capsuled to avoid mutual contact of these components. These methods, however, do not satisfy the requirements for the preservability and thermal coloring performance for use in practice.
Japanese Laid-Open Patent Application 57-142391 discloses an alternative method for minimizing the contact of a diazo compound and a coupling component, by which a layer for a diazo compound and a layer for a coupling component are overlaid, and an intermediate resin layer comprising a thermofusible material is interposed between the two layers to separate the two layers.
Japanese Laid-Open Patent Publication 4-3315 discloses that a binder agent which is alkali-soluble and becomes insoluble in contact with an acid is used in a base-containing development agent layer.
The former method disclosed in Japanese Laid-Open Patent Application 57-142391, however, has the shortcoming that the separation effect of the intermediate resin layer is not sufficient for use in practice, and the latter method disclosed in Japanese Laid-Open Patent Publication 4-3315 cannot prevent the occurrence of the precoupling phenomenon in the thermal development diazo copying material during the preservation thereof prior to use because the binder also contains a base, and the binder agent does not become insoluble to a sufficient extent for use in practice.